Types of Databases - Hierarchical
Hierarchical databases are like 3-dimensional extensions of a flat database ... Instead of everything being recorded on a single sheet of paper, imagine there are several sheets of paper organized like chapters in a book.
Picture the top sheet of the hierarchy as the table of contents, with each subsequent sheet being a more detailed account of the data organized into chapters, subchapters, etc...
The problem with this type of design is that some data do not fit into the hierarchy.
Imagine the database were a cookbook and you had a piece of data in the form of a bible story. What chapter do you put it under? If you bury the story , how would someone picking up the book for the first time know what chapter to look in to find it?